JPH0897280A - Method for manufacturing semiconductor device - Google Patents

Abstract

(57) [Abstract] [Purpose] Aluminum can be embedded in fine via holes, and the reliability of semiconductor devices is improved. [Structure] A silicon oxide film 2 is deposited on a silicon substrate 1, titanium 3 is deposited on the silicon oxide film 2, and then TiN 4 is deposited. Further, an aluminum film 5 is further deposited thereon, a part of titanium 3, TiN 4 and aluminum film 5 is etched, a silicon oxide film 6 is deposited thereon, and TiN 7 is deposited thereon. The substrate in this state is dry-etched to form a through hole 8 for a via hole in the silicon oxide film 6 and TiN 7 for establishing electrical connection with the aluminum film 5. The substrate having the through holes 8 opened is exposed to a tetrakisdimethylaminotitanium atmosphere so that the tetrakisdimethylaminotitanium 9 is adsorbed to the TiN 7 and the silicon oxide film 6 on the side wall of the through holes 8.
The aluminum layer 10 is deposited by the CVD method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to embedding aluminum in fine via holes or grooves in a wiring forming process using aluminum (Al).

[0002]

2. Description of the Related Art Conventionally, in a method of manufacturing a semiconductor device, a refractory metal or refractory metal compound is deposited in a via hole on an insulating film by a sputtering method, and wiring is formed on the deposited refractory metal or refractory metal compound. Aluminum, which is a film, is deposited by the sputtering method.

However, LSI (Large Scale Integrated Circuit)
The higher aspect ratio of via holes and trenches has progressed with the progress of higher integration, and aluminum cannot be embedded in the via holes and trenches by the sputtering method.
VD (Chemical Vapor Deposition)
ion: vapor phase chemical growth) is attempted to embed aluminum. Here, the aspect ratio indicates the ratio between the thickness of the integrated circuit substrate and the diameter of the via hole or groove.

"Deep Submicron Com
tact Hole Filling by Al C
VD at Low Temperature "(K.
Sugai, et al. , Electrochemi
cal Society, Extended Abst
racts, Volume 93-1, P.R. 482,4
83) describes a method in which a base adhesion layer TiN which is a refractory metal compound is deposited by a collimator sputtering method, and aluminum is deposited thereon by a CVD method.

In this method, the diameter of 0.3 μm was experimentally determined.
It has been confirmed that aluminum is embedded in a via hole having an m and an aspect ratio of 2.7. The collimator sputtering method is a method in which a mesh is arranged between a target and a substrate, and material particles whose movement direction is mainly perpendicular to the substrate surface are deposited on the substrate.

Further, Japanese Patent Laid-Open No. 5-93273 discloses
CV after exposing the SiO ₂ substrate to the organic titanium gas atmosphere
It is disclosed that by forming an aluminum film by the D method, an aluminum film having a smooth surface shape can be obtained.

[0007]

In the above-mentioned conventional method for manufacturing a semiconductor device, aluminum is deposited by the collimator sputtering method and the aluminum CVD method. In the collimator sputtering method, the diameter is 0.25 μm and the aspect ratio is 3 It has been confirmed from experimental results that aluminum cannot be embedded inside the via hole when the aluminum is embedded in a fine via hole of 0.3 or more.

Therefore, in the above method, there is a problem that the yield of the semiconductor device is lowered and the productivity is lowered because the disconnection occurs in the wiring having the via hole of the high aspect ratio.

Further, when aluminum is formed by the CVD method after exposing the silicon oxide (SiO ₂ ) substrate to the organic titanium gas atmosphere, aluminum can be formed in fine via holes having a diameter of 0.3 μm or less, Since pure Al is deposited at that time, electromigration of the wiring (electromigration)
on) resistance is low, and the reliability of the semiconductor device is significantly low.

Therefore, an object of the present invention is to solve the above problems and to provide a method of manufacturing a semiconductor device in which a fine via hole can be filled with aluminum and the reliability of the semiconductor device can be improved. is there.

[0011]

A method of manufacturing a semiconductor device according to the present invention comprises a step of depositing an insulating film on a conductive layer on a semiconductor substrate, a step of depositing a refractory metal film on the insulating film, Forming a through hole for connection with the conductive layer in the insulating film and the refractory metal film, exposing the semiconductor substrate in which the through hole is formed to a halogen-free titanium compound gas atmosphere, And a step of forming an aluminum thin film on the semiconductor substrate by a vapor phase chemical growth method.

[0012]

In Al-CVD, many small islands are formed in the early stage of growth, and they are gradually fused to form a film. Moreover,
It has been found that the minimum film thickness when a continuous film is formed is the minimum radius of a via hole in which it can be embedded.

Since CVD utilizes the chemical reaction of the raw material on the surface of the substrate, the density and size of the islands formed differ depending on the surface condition of the substrate, and as a result, the limit of embedding depends on the surface condition of the substrate. It is expected that.

On the other hand, from the viewpoint of improving the reliability of the Al wiring, it is necessary to form an aluminum film on the refractory metal layer or the refractory metal compound. Therefore, Ti and Ti
When N or TiW was exposed to tetrakisdimethylaminotitanium and an aluminum film was formed thereon, an aluminum film having a minimum film thickness of 1400Å was deposited.

On the other hand, silicon oxide (SiO ₂ )
When the substrate was exposed to tetrakisdimethylamino titanium and an aluminum film was formed on it, the minimum film thickness was 50
A 0Å aluminum film was deposited.

Therefore, it is impossible to embed aluminum in a via hole having a diameter of 0.28 μm or less on Ti or TiN exposed to tetrakisdimethylaminotitanium or TiW, and a silicon oxide substrate exposed to tetrakisdimethylaminotitanium. Diameter 0.1 above
It has been found that aluminum can be filled up to a via hole of μm.

As described above, it has been newly found that in the case of a fine via hole having a diameter of 0.28 μm or less, aluminum can be embedded in the via hole by exposing the sidewall of the via hole to SiO ₂ and exposing it to the titanium compound gas.

Therefore, in the present invention, in order to simultaneously bury aluminum in a fine via hole and achieve high reliability of wiring, a refractory metal or a refractory metal compound is deposited on SiO ₂ before the via hole for connection is opened. Are deposited on.

After that, by etching the refractory metal or the refractory metal compound together with SiO ₂ , the side wall of the via hole for connection can be made SiO ₂ . In addition, a structure in which a refractory metal is deposited is formed to improve reliability in areas other than the via holes for connection.

After that, the substrate having the above structure is exposed to a titanium compound gas atmosphere, and aluminum is deposited by the CVD method, whereby fine via holes can be embedded and highly reliable wiring can be performed.

[0021]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a manufacturing process according to an embodiment of the present invention. FIG. 1 (a) shows T which is a refractory metal compound.
A process of depositing iN on SiO ₂ which is an insulating film is shown.
FIG. 1B shows a process of forming a via hole.
(C) shows the step of adsorbing tetrakisdimethylaminotitanium on TiN and SiO ₂ , and FIG. 1 (d) shows the step of forming aluminum wiring.

In these figures, 1 is a silicon substrate, and 2 and 6 are silicon oxide (SiO 2) on the silicon substrate 1.
₂ ) film, 3 is titanium (Ti), 4 and 7 are TiN, 5 is an aluminum (Al) film which is a conductive layer, 8 is a through hole for a via hole, 9 is tetrakisdimethylamino titanium, 10
Indicate aluminum (Al) layers, respectively.

Embedding of aluminum in a fine via hole or groove in a wiring forming process using aluminum according to an embodiment of the present invention will be described with reference to FIG.

First, a silicon oxide film 2 of about 500 nm is deposited on a silicon substrate 1, titanium 3 of about 100 nm is deposited on the silicon oxide film 2, and then TiN 4 of about 1 nm is deposited.
00 nm is deposited.

Further, an aluminum film 5 of about 1 is formed thereon.
After depositing μm, a part of titanium 3, TiN 4, and aluminum film 5 is etched, and a silicon oxide film 6 as an insulating film is deposited thereon to a thickness of about 2 μm, and TiN is deposited thereon.
7 is deposited to a thickness of about 100 nm [see FIG. 1 (a)].

After that, the substrate in the above state is subjected to dry etching to form a through hole 8 for a via hole in the silicon oxide film 6 and the TiN 7 so as to establish conduction with the aluminum film 5 [FIG. 1 (b)]. reference].

The substrate in which the through holes 8 are formed is placed in a tetrakisdimethylaminotitanium atmosphere of 1 mTorr at room temperature for 5 mi.
Then, the exposed TiN 7 and the exposed silicon oxide film 6 on the sidewall of the through hole 8 are adsorbed with tetrakisdimethylaminotitanium 9 [see FIG. 1 (c)].

An aluminum layer 10 is formed by a CVD method on the substrate on which the tetrakisdimethylaminotitanium 9 is adsorbed.
Deposit. Dimethyl aluminum hydride is used as a raw material for the deposition condition at that time, the deposition temperature is set to 160 ° C., and the pressure is set to 1 Torr to deposit the aluminum layer 10 [see FIG. 1 (d)].

As a result, the refractory metal and the refractory metal compound were not formed on the side walls of the via holes 8 for via holes, so that the aluminum for the via holes 8 for via holes having a diameter of 0.1 μm and an aspect ratio of 6 was formed. Embedding can be realized.

In the above-mentioned method, the aluminum embedded in the via hole is also deposited on the TiN 7, so that the electromigration resistance can be improved more than in the conventional example, and the semiconductor device having high reliability and high yield can be obtained. it can.

TiN7 deposited on the silicon oxide film 6 which is an insulating film before opening the via hole is replaced with Ti or Ti.
Even if other refractory metal or refractory metal compound such as W is used, the same effect as described above can be obtained.

Furthermore, the temperature, pressure and time for exposing the substrate having the through holes 8 exposed to the tetrakisdimethylaminotitanium atmosphere are TiN 7 and the silicon oxide film 6 on the side wall of the through holes 8.
Any conditions may be used as long as the tetrakisdimethylaminotitanium 9 is adsorbed on, and the conditions are not particularly specified.

Although the above-mentioned method defines the film forming conditions for depositing the aluminum layer 10 by the CVD method, the same effect as above can be obtained under other conditions. For example, trimethylamine alane or triisobutylaluminum is used as a raw material, the film forming temperature is 70 ° C. to 280 ° C., the pressure is 0.1 to 20.
The aluminum layer 10 can be deposited by using Torr.

In addition, in the above-mentioned method, tetrakisdiethylaminotitanium, titanium dicyclopentadienyl titanium azide, bisdimethylaminodicyclopentadienyl titanium, and tetratrimethylsilylmethyl titanium are pretreated by a halogen-free titanium compound gas. Even if one of the atmospheres is used and tetrakisdiethylaminotitanium is adsorbed to the silicon oxide film 6 on the side wall of the TiN 7 and the through hole 8, the improvement of the embedding of aluminum in the through hole 8 is confirmed by the experiment as described above. .

By performing the pretreatment with the titanium compound gas containing no halogen, it is possible to prevent the corrosion of the aluminum thin film due to residual chlorine when the titanium compound gas containing halogen is used.

As described above, TiN7 is deposited on the silicon oxide film 6 before the through hole 8 for the via hole for establishing conduction with the aluminum film 5 is formed, and the through hole 8 is formed in the silicon oxide film 6 and TiN7. After opening, TiN 7 and tetrakisdimethylamino titanium 9 are adsorbed on the silicon oxide film 6 on the side wall of the through hole 8 and then an aluminum layer 10 is deposited by a CVD method to remove aluminum from a high aspect ratio fine via hole. It is possible to embed and form aluminum on the refractory metal film in the wiring part. Therefore, a semiconductor device with high yield and high reliability can be obtained.

[0038]

As described above, according to the present invention, an insulating film is deposited on a conductive layer on a semiconductor substrate and then a refractory metal film is deposited, and a conductive layer is formed on the insulating film and the refractory metal film. After forming a through hole for connection of the semiconductor substrate, the semiconductor substrate is exposed to a halogen-free titanium compound gas atmosphere to deposit titanium atoms on the exposed surfaces of the insulating film and the refractory metal film, respectively, and then vapor-phase chemical growth is used to deposit aluminum. By forming a thin film, fine via holes can be filled with aluminum,
There is an effect that the reliability of the semiconductor device can be improved.

[Brief description of drawings]

FIG. 1A is a diagram showing a process of depositing TiN which is a refractory metal compound on SiO ₂ which is an insulating film, FIG. 1B is a diagram showing a process of forming a via hole, and FIG. FIG. 6 is a diagram showing a process of adsorbing tetrakisdimethylaminotitanium on SiO ₂ , and FIG. 7D is a diagram showing a process of forming aluminum wiring.

[Explanation of symbols]

 1 Silicon Substrate 2,6 Silicon Oxide Film 3 Titanium 4,7 TiN 5 Aluminum Film 8 Through Hole for Via Hole 9 Tetrakisdimethylaminotitanium 10 Aluminum Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akiko Kobayashi 5-8-1, Yotsuya, Fuchu-shi, Tokyo Within Nichiden Anerva Co., Ltd. (72) Inventor Tadaaki Yako 5-1 Sokai-cho, Niihama-shi, Ehime Sumitomo Chemical Industrial Co., Ltd. (72) Inventor Hideko Kadokura 5-1 Sokai-cho, Niihama-shi, Ehime Sumitomo Chemical Co., Ltd.

Claims (5)

[Claims] 1. A method of depositing an insulating film on a conductive layer on a semiconductor substrate, a step of depositing a refractory metal film on the insulating film, and a step of depositing the conductive layer on the insulating film and the refractory metal film. Forming a through hole for connection, exposing the semiconductor substrate having the through hole to a titanium compound gas atmosphere containing no halogen, and forming an aluminum thin film on the semiconductor substrate by a vapor phase chemical growth method A method of manufacturing a semiconductor device, comprising: 2. The method of manufacturing a semiconductor device according to claim 1, wherein the insulating film is made of a silicon oxide film. 3. The halogen-free titanium compound gas is selected from tetrakisdimethylaminotitanium, tetrakisdiethylaminotitanium, dicyclopentadienyl titanium azide, bisdimethylaminodicyclopentadienyl titanium, and tetratrimethylsilylmethyl titanium. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the method comprises one of the two. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the refractory metal film is made of one of refractory metal and refractory metal compound. 5. The refractory metal film is made of Ti, TiN and T.
4. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is made of any one of iW and iW.